1. Field of the Invention
The present invention relates to a technique for evaluating the communications quality of voice packets. For example, the present invention can be applied to internet telephony or the like.
2. Description of Related Art
Techniques for voice communications utilizing networks such as the internet or the like are known. In voice communications of this type, voice information is compressed and encoded; this information is further formed into packets, and is transmitted via a network.
In the case of such voice communications via a network, the voice quality deteriorates as a result of packet dropout (i. e., packet loss), delay in transmission, fluctuation in transmission delay (i. e., jitter) and the like. The frequency of occurrence of packet dropout and the magnitude of the fluctuation in transmission delay vary at all times according to the network traffic. Accordingly, the voice quality varies according to such variations in frequency and magnitude.
In the case of multi-media communications that handle voice, images and the like, lossly compression is commonly used as the compression method. For example, a high compression rate of several tens of times to several hundred times can be obtained by lossly compression. In the case of lossless compression, on the other hand, a compression rate of several of times can be obtained. However, in the case of data compressed using lossly compression, there is a high probability that some of the information will drop out when the data become to be extracted. Accordingly, a technique for the objective evaluation of the effects of such dropout on communications quality is needed.
Currently, however, no technique exists for the objective measurement of voice quality in real time.